Salt mine

“ The quantity of rock-salt mined was small compared with coal. No mine in the district yielded above 40,000 tons per annum.
Rock-salt is more free from danger than most kinds of mining; no explosions occur, for there are no deleterious gases, and accidents are rare. In a general way103 the rock-salt strata are remarkably free from carbonic acid gas, and in only one instance in Northwich, and twice at Meadow Bank, Winsford, does fire-damp appear to have been met with, and then only at pipe veins and in very small quantity. ”

“ The salt-mines of Cheshire, and the brine-pits of Worcestershire, according to the best authority, not only supply salt sufficient for the consumption of nearly the whole of England, but also upward of half a million of tons for exportation. Rock-salt is by no means confined to England, it is found in many countries, especially where strata of more recent date than those of the coal measures abound. Though in some instances the mineral is pure and sparkling in its native state, it is generally dull and dirty, owing to the matter with which it is associated. ”

“ The pumping from the reservoirs formed by the flooding of the old mines does not empty these huge receptacles, as the place of the brine is continuously retaken by fresh water, which naturally gravitates to these centres and proceeds to dissolve and take up its quota of rock-salt. When a subsidence occurs on the site of these old workings it is of the most destructive nature, and as all the top-rock mines were in the neighbourhood of streams and brooks, the surface waters flow into the cavity until it is filled to the level of the earth and allows the streams to pursue their proper course. ”

“ The story of the exploitation of the top and bottom beds is one that is soon told. The top bed was worked until the mines began to fall in and the subsequent breaking in of fresh water converted the old workings into brine reservoirs. In 1779, the discovery of the lower bed of rock-salt at Lawton prompted the owners of the Marston Mine at Northwich to sink below the top bed in which they were working, and, in 1781, a trial shaft which was sunk from the top mine by means of a horse gin, demonstrated the existence of the bottom deposit in that district. ”

“ Where the salt deposits are composed of a mineral that is white, odourless, and practically pure, as in the Wieliezka system and the mines of Rumania, and particularly if labour is abundant and cheap, and the industry is a monopoly of the State, rock-salt mining will always hold its own. ”

“ From this little town is procured the salt which is brought from Timbuctoo to Jenné, and thence dispersed through all the Soudan. The salt mines, as I was informed, are three feet and a half or four feet below the surface of the ground; the salt is in thick strata, and is brought out in blocks, after which it is split into cakes of the size I have already described. These mines are the wealth of the country; they are worked by negro slaves, superintended by Moors, who live entirely upon rice and millet, brought from Timbuctoo, and cooked with camels’ flesh dried in the sun. ”

“ Leonard Bauman, Clarence, Iowa—The most productive salt region of the United States is the Saginaw salt district, Michigan. The most famous and productive salt mines in the world are those of the rock salt region of Wieliczka, in Gallicia, a province of Polish Austria. Great chambers have been excavated in the solid salt, some of them fully 150 feet in height, and of immense length and breadth. ”

“ The most interesting salt-mine is that of Wieliczka, near Cracow, in Galicia; it has been celebrated for centuries, and has been worked for the last six hundred years. This wonderful mine is excavated in a ridge of hills at the northern extremity of the chain which joins the Carpathian mountains. When the stranger reaches the mine there bursts upon his view a little world, the beauty of which is scarcely to be imagined. ”

“ The methods employed in working out the rock-salt offer nothing worthy of notice. The operation of blasting is applied to the separation of large masses from the body of the rock, and these are afterwards broken down by the mechanical implements in common use. The present number of mines is eleven or twelve, from which there are raised, on an annual average, fifty or sixty thousand tons of rock-salt. The greater part of this quantity is exported to Ireland and the Baltic: the remainder is employed in the Cheshire district in the manufacture of white salt by solution and subsequent evaporation. ”

“ The salt mines a little distance beyond Absam, with their crystalline grottoes and the subterranean salt lake, provide an interesting and unique experience for the enterprising traveller who comes to the Salzberg. There is not much difficulty in obtaining admission to the mines, a small fee being charged each visitor for guides, torches, and the rowers of the boat on the lake. The circumstance that the mines were known and worked in the eighth century is not the least interesting fact connected with them ”

“ He beholds a spacious plain containing a kind of subterranean city, with houses, carriages, and roads, all scooped out of one vast rock of salt, as bright and glittering as crystal, while the blaze of the lights continually burning for the general use is reflected from the dazzling columns which support the lofty arched vaults of the mine, which are beautifully tinged with all the colours of the rainbow, and sparkle with the lustre of precious stones, affording a more splendid and fairy-like aspect than anything above ground can possibly exhibit. ”

“ Platinum ores running from 80 to 85 per cent are found with gold and other metals. Iron is widely distributed; also copper; often with gold, tin, and in primitive rock formation. Manganese, lead, mercury, sulphur, zinc, antimony, arsenic, nitre, alum, exist, but are not much worked except sulphur, which is taken from some volcanoes. The working of the salt mines is a government monopoly, rock salt and springs existing in large numbers. From the Zipaquirá salt mine in Cundinamarca the Government receives a revenue of approximately $1,000,000 a year. ”

“ The primitive methods that characterized the brine industry have been adhered to with equal tenacity in the winning of rock-salt. It is extraordinary that, in the manufacture and in the mining of salt, each successive generation of salt-men, in inheriting their methods from their forefathers, or adapting them from the miners of another country, have always preserved the intense conservatism that appears to be inseparable from the industry, and have resisted all innovations that have promised to simplify or expedite their labours. ”

“ The roof of a mine is held up by columns of salt which are left in position for that purpose, but they frequently give way and the buildings above them are wrecked.
The coarser kinds of rock-salt are still taken out in lumps. You may often see pieces in the Cheshire fields which farmers have put there for cattle to lick. For salt contains health-giving properties, and salt-mining is not injurious to health as coal-mining is. Brine baths have been made at Nantwich for people suffering from certain diseases. ”

“ Its windings are so numerous and intricate, that workmen have frequently lost their way: the lights they carried have been burned out, and they have perished before they could be found. The salt is taken from these mines in blocks so large as, sometimes, to measure nine feet in length, four feet in width, and two or three feet in thickness. In the year 1780, the greatest depth to which the workmen had penetrated was about 320 yards, and the mass of salt was considered to be in some places more than 240 yards thick, and to extend at least three leagues. ”

“ The number of workmen employed in the various operations underground, exclusive of those above, is upward of a thousand. The amount of salt annually dug out is two hundred millions of pounds, which, at the average market value, would be worth ten millions of gulden. Immense as this yield is, it is inconsiderable, taking into view the unlimited capacity of the mines. With proper machinery and a judicious investment of labor the quantity of salt that might be excavated is almost beyond conjecture. ”

“ The Cheshire mines are from 50 to 150 yards below the surface. The number of salt-beds is five; the thinnest of them being only about six inches, while the thickest is nearly forty feet. Besides these vast masses, there is a large quantity of salt mixed up with the marl beds that intervene. The method of working the rock-salt is like that adopted for the excavation of coal; but it is much more safe and pleasant to visit these than the other, owing to the roof of the excavations being much more secure, and the absence of all noxious gases, with the exception of carbonic acid gas. ”

“ It was demonstrated that the machine produced more salt in a given time, and that the waste of about 25 per cent. of the salt attendant upon manual labour and the use of picks was saved, but as the supply of salt is practically inexhaustible, and there is no limit set upon the time of winning it, and as man-power, especially convict man-power, is cheaper than machinery, the authorities soon reverted to the old system. In the Slanic mine, in which the salt is crystalline, white, and almost absolutely pure, the free labourers, of whom about 500 are employed, are divided into gangs of six men. ”

“ One of the most remarkable salt mines in the world is at Wieliczka, near Warsaw, Poland. It has been worked since 1252, and at one time furnished the principal revenue of the kingdom. A vast number of people inhabit the subterranean passages of this mine, and are governed by laws and magistrates of their own. Each miner is allotted a little cell, where he dwells and rears his family. As many as eighty horses are kept in this underground republic to carry to and fro along the immense corridors which are supported by pillars of salt. ”

“ The substance with which bitumen seems to have the most constant and most remarkable relations, is sea-salt; so that almost all the countries most abundant in petroleum, as Italy, Transylvania, Persia, the environs of Babylon, the region of the Dead Sea, &c., contain salt mines, or lakes, or exhibit saline efflorescences. Iron pyrites is often impregnated with petroleum, or contains a bituminous nucleus. ”

“ Even in this country, when the old open-pan system of evaporating salt from brine produced only two tons of salt for the consumption of a ton of fuel, rock-salt could be raised, purified, and marketed in competition with white salt, but the modern boiling processes have effected such substantial improvements and consequent economical advantages, that the rock-salt industry appears to be doomed to decay. ”

“ But the mining of the upper bed of salt by man does not account for the subsidences here recorded. The name of the dangerous miner is "water." When water reaches the upper bed of salt it dissolves it as water does snow. Water can take in 26 degrees of salt and no more, and then it is called brine. Underneath Northwich is a sea of brine which lies on the top of the upper bed of salt rock. From this brine white salt is made by a process of evaporation, and that is why all over Northwich you see numbers of pumping stations which pump up the brine as fast almost as it is made. ”

“ About six hundred thousand quintals of salt are dug annually out of the mines of Cracow. The worst and cheapest is called green salt, from its greenish color, occasioned by a heterogenous mixture of a grayish mineral, or clay, and entirely consists of salt crystals of different dimensions. A finer sort is dug out in large blocks; and the third kind is the sal gemmæ, or crystal salt, which is found in small pieces interspersed in the rock, and, when detached from it, breaks into cubes of rectangular prisms. ”

“ Some of the lakes of the Great Basin are dense brines from which various substances are being precipitated. The economic importance of these natural reservoirs of brine and of various soda salts is great, and will become more and more important as transportation facilities increase. Great Salt Lake, it has been estimated, contains 400,000,000 tons of common salt and 30,000,000 tons of sodium sulphate in solution. During the past ten years about 40,000 tons of common salt have been harvested from it annually. ”

“ The ascertained area of the mine is several acres; the depth of the deposit is unknown. The first shaft was sunk a hundred feet; below this a shaft of seventy feet fails to find any limit to the salt. The excavation is already large. Descending, the visitor enters vast cathedral-like chambers; the sides are solid salt, sparkling with crystals; the floor is solid salt; the roof is solid salt, supported on pillars of salt left by the excavators, forty or perhaps sixty feet square. When the interior is lighted by dynamite the effect is superbly weird and grotesque. ”

“ The miners live in villages among the hills. They have a most unhealthy complexion, but do not appear to be subject to any particular disease. They receive a rupee for every twenty maunds of salt brought to the surface, a task which may be performed by a man, his wife and child, in two days. In those mines where the mineral is near the surface, it is hewn into blocks of four maunds, two of which load a camel, but it is usually broken in small pieces. This salt holds a high reputation throughout India, with native practitioners, from its medical virtues. ”

“ In this area the production is naturally limited by want of transport and the small local demand, the total output from the quarries being about 16,000 tons per annum. A small quantity of salt (generally about 4000 tons a year) , is raised also from open quarries in the Mandí State, where the rock-salt beds, distinctly impure and earthy, lie near the junction between Tertiary formations and the older unfossiliferous groups. ”